Numerous possible methods of formulation are known from application technology for being able to incorporate slightly water-soluble phytosterols and phytostanols which are used as cholesterol-lowering agents into food preparations or pharmaceutical products.
Numerous patent applications describe how the availability of sterols can be improved via reducing particle sizes, principally by micronization. For instance, German laid-open application DE 102 53 111 A1 describes pulverulent phytosterol formulations having a median particle size of 0.01 to 100 μm which may be readily redispersed in water. Preferably, use is made of hydrophilic auxiliaries as protective colloids. For producing the powders, use is made of organic solvents to the disadvantage of ecology and acceptability. International application WO 2005/074717 A1 also uses a type of protective colloid by embedding sterols into a matrix which contains proteins and carbohydrates. The total sterol content in the formulation, however, is small, owing to the high fraction of auxiliaries.
A further method for producing a sterol dispersion in which the particle size distribution of the sterols is from 0.1 to 30 μm, may be found in the international applications WO 03/105611 and WO 2005/049037. As in this method, frequently micronization of the sterol particles alone is insufficient in order to achieve good incorporability. Although the bioavailability of the finely dispersed particles may be improved by increasing the surface area, especially the micronized particles are poorly wettable, aggregate readily and generally float on aqueous surfaces. Frequently, the ground sterol can only be dispersed in a drink using special methods, for which intense mixing is necessary. However, these apparatuses are not usually available to the end user, the food manufacturer.
Therefore, many manufacturers combine micronization of sterols with the additional use of emulsifiers. An example thereof are the preparations claimed in European patent EP 0897671 B1 having sterols and sterol esters having a particle size of a maximum of 15 μm in a mixture with selected emulsifiers, wherein the weight ratio of emulsifier to sterol in the aqueous phase is less than 1:2.
In the international patent application WO 03/086468 A1, pulverulent sterol ester formulations having a low protein content and mono- and diglycerides as emulsifiers are disclosed. Even if these are distinguished by good acceptability and have already been known as food emulsifiers over a long time period, attempts are made to decrease the amount of the emulsifiers, or even to avoid them completely, since emulsifiers also affect the bioavailability of other substances present in the foods or can adversely affect the stability of the formulations.
Other methods of improving the solubility and dispersibility, such as formulation as emulsions, microemulsions, dispersions, suspensions or complexing with cyclodextrins or bile salts are presented in international patent application WO 99/63841 A1. Proposed supports are PEG, PVP, copolymers, cellulose ethers and cellulse esters. Also, direct use of food base materials as supports for pulverized sterols in the form of a premix is disclosed by EP 1 003 388 B1. The selection of proteins as support substances for non-esterified sterols and stanols is disclosed in WO 01/37681.
In particular, processing non-esterified sterols and stanols which are still very much more hydrophobic than their esterified derivatives makes high demands on the production method. Free ground sterols in addition, have the disadvantage that they have a low minimum ignition energy (MIE<3 mJ), and therefore these products are categorized as extremely sensitive to ignition. Therefore, when free sterols are used, corresponding safety precautions must be heeded.
A possible method of producing sterol-containing microparticles can be found in European patent EP 1148793 B1. It is based on high-energy homogenization. However, a powder produced thereby based on aqueous suspension media has an inadequate homogeneity and can only be redispersed with difficulty. A disadvantage of many sterol-containing powder formulations is the agglomeration behavior of the free sterols on storage. During storage, especially if they are stored under pressure, severe clumping or lump formation is observed, and the solid uncontrolled agglomerates must again be comminuted in order then to be able to be processed.
In the international patent application WO 2006/020980A1, agglomerates of sterol particles are described. The production method is a size-enlargement granulation of adhesive granules in which the micronized sterol particles are wetted with a suspension medium in which a binder is in part or completely dissolved. The suspension medium is removed after the wetting, in such a manner that the remaining agglomerates have a size of 150 to 850 μm. This method requires a high use of apparatus and must be controlled very precisely, in order that the agglomerates produced have the desired stability.
It was an object of the present invention to provide sterol-containing formulations having a high content of sterols and/or stanols, which may be produced using simple and rapid processes, and enable good and rapid dispersion and incorporation of non-esterified sterols and/or stanols in foods, wherein the formulations should have good sensory and organoleptic properties in the foods.